1. Field of the Invention
The present application is an apparatus for freeing a manhole cover frame from pavement in which it is embedded and a method of removing the manhole cover frame from pavement.
2. Description of the Prior Art
Underground utilities, such as electrical cables, gas lines, and water lines are in widespread use and are often accessible by means of manholes that are comprised of manhole covers set in manhole frames which are embedded in pavement. Both the manhole covers and the manhole cover frames are heavy, rugged items that must withstand the very great weight of vehicles traveling over them.
From time to time it is necessary to remove from the pavement both the manhole cover and the embedded frame within which the manhole cover is set. Manhole cover systems have to be removed for a variety of reasons. For example, realignment of a road bed requires lifting of the manhole cover and frame. Sometimes it is necessary to upgrade manhole covers to provide lockable systems. These systems also require a new manhole cover frame, as well as a new cover. Sometimes it is necessary replace manhole systems with waterproof manhole covers and manhole cover frames.
In conventional practice there are heavy-duty devices designed to lift manhole covers from their frames. As difficult as this sometimes is, the removal of a manhole cover frame from the pavement in which it is set is even more difficult. Currently manhole cover frames are removed by utilizing a jackhammer that is worked about the periphery of the manhole cover frame to break up the pavement into which the frame is set. The breaking up of the pavement about the periphery of the manhole cover frame is slow, backbreaking work. Even worse, removal of the manhole cover system in this manner damages the foundation on which the frame sits. That is, by using a jackhammer to break up pavement about the periphery of a manhole cover frame, cracks are often formed in the pavement that later admit moisture and subject the surrounding pavement to subsequent degradation due to the damage to the pavement inflicted by the breaking up the pavement about the periphery of a manhole cover.
Damage to the pavement is unacceptable, as loads from heavy traffic must be transferred to the road base through the foundation provided by the pavement. For this reason, in conventional practice the material surrounding the frame has to be over excavated and built back up again before installing the replacement frame. This is all very laborious, expensive, and time consuming.